Three-dimensional nanocomposite of reduced oxide graphene (rGO) and Cu/Cu2O nanocrystal (3D Cu/Cu2O@rGO) was synthesized via a one-step low-temperature co-reduction method and further used as an electrochemical sensor for detecting ractopamine (RAC). In comparison with pristine Cu2O nanospheres and porous rGO, ractopamine antibody (RAC(anti)) prefers to anchor onto the surface of 3D Cu/Cu2O@ rGO nanocomposite because of its multi-functionality, which subsequently leads to more sensitive RAC detection. The developed electrochemical biosensor based on 3D Cu/Cu2O@rGO nanocomposite adsorbed with RAC(anti) showed a low detection limit of 7.5 pg mL(-1) within the range of 0.1 ng mL(-1) to 10 ng mL(-1) for detecting RAC. Furthermore, interference from other lean meat powders, urine components, and metal ions, such as salbutamol, clenbuterol hydrochloride, uric acid, urea, K+, Na+, Mg2+, and Ca2+, associated with RAC analysis can be effectively inhibited. The strategy offers a new pathway for rapid RAC analysis and shows a promising prospect in food safety. (C) 2015 Elsevier Ltd. All rights reserved.